For example, it is known to use an electrophotographic image forming apparatus, such as a copier, printer or facsimile machine, form images on the front and back sides of sheets, and bind a bundle of the sheets to produce a book. In the case of using an image forming apparatus in such a manner, highly accurate positioning of an image on a sheet is required. In other words, high quality image forming free from position deviation of images on the front and back sides of a sheet is required. Further, in the case of cutting the edge portions of plural sheets after binding, images may be partially cut off to be missing if the positions of edge portions of formed images are not correctly aligned.
In general, a sheet feeding device is provided with regulating members to regulate the sides of sheets stored in a sheet feeding tray, along the transverse direction. When regulating members are accurately collided with sheets for regulation, almost no shift or angle deviation of sheets is caused. However, as disclosed in Japanese Unexamined Patent Application Tokkaihei No. H05-132240, an image forming apparatus is, in general, provided with a plurality of sheet feeding devices, having a sheet loading table, for respective sizes of sheets, wherein when an opening and closing cover arranged on a sheet feeding device is opened, or when a sheet feeding tray is drawn out from the main body of a sheet feeding device, a sheet loading table with sheets stacked thereon is automatically falls to a lower position so that sheets can be supplied. Therefore, even when adjusting the position of regulating members, adjustment is carried out in a state where a sheet loading table has been lowered to a lower position. However, even trying to regulate sheets in the transverse direction in a state where a sheet loading table has been lowered to a lower position, the sheets are not at the sheet feeding position, but are below and too far from the sheet feeding position, which makes regulation in the transverse direction incorrect and cannot achieve a high accuracy.
That is, regulating members may be deformed depending on the accuracy of manufacturing, change with time, etc., and accordingly the distance between regulating members deviates between an upper position where sheets are actually fed and a lower position to which a sheet loading table has been lowered. Consequently, even adjusting regulating members correctly at a lower position to which a sheet loading table has been lowered, when sheets have risen to a position for actual sheet feeding thereafter, a gap may be created along the transverse direction between the side of the sheets and a regulating member to cause angel deviation of the sheets, prohibiting accurate regulation of the position of the sheets. Herein, angle deviation of sheets means a state where sheets are located not parallel to the sheet conveying direction, and have an angle deviation to the conveying direction.
Particularly, the angle deviation is significant in a large capacity tray (LCT) with a large rise and fall amount of a sheet loading table.
For solution of problems, as described above, and adjustment of regulating members that is sufficiently accurate, it is necessary that sheets are held at a sheet feeding position at the time of adjustment. Herein, the adjustment can be made by an input via an operation unit, by opening an opening and closing cover of a sheet feeding device, or by drawing out a sheet feeding tray. On the other hand, when supplying sheets, it is necessary that a sheet loading table falls and then sheets can be supplied. An object of the invention is to provide a sheet feeding device that can feed a sheet at a highly accurate position by adjusting the positions of regulating members with a simple mechanism and an image forming apparatus provided with such a sheet feeding device.